1. Field of the Invention
The present invention relates to a method for covering an electric component with a resin, more particularly, to a method for covering an electric element and parts of terminals of said electric component with a coating resin.
2. Description of the Prior Art
Generally, there is an electric component wherein an electric element is covered with a coating resin. As reasons for covering the electric element with the coating resin, the following are given.
The first reason is for protecting the electric element against an impact applied to a surface part thereof. If not covered with the coating resin, when an impact is applied to the electric element, the electric component element may be broken or chipped, and it is likely to become a source of trouble. Thus, by covering with the coating resin, an impact applied to the electric element is cushioned.
The second reason is for protecting the electric element against moisture, dust and the like. If not covered with the coating resin, moisture, dust and the like in the air maybe stuck on the electric element, and it is likely to deteriorate the characteristic of the electric element. Thus, the electric element is covered with the coating resin so as not to allow moisture, dust and the like in the air to stick on the electric element.
As a material of the coating resin, a resin such as epoxy resin or the like is used.
After connecting and fixing the electric element with terminals, the electric element and parts of the terminals are dipped into a melted resin, the resin is stuck on them, and the resin is hardened, whereby the electric element is covered with the coating resin.
When the electric component is covered with the coating resin, the electric component is deeply dipped into the melted resin so as to cover the electric element with the coating resin completely. Thus, when the electric element is regarded as an upper part of the electric component, there is a case wherein lower parts below the predetermined positions on the terminals are covered with the coating resin. In this case, with the coating resin stuck on the lower parts, holes for receiving the terminals formed at a substrate for mounting the electric component may become filled, which is likely to cause poor soldering.
Therefore, conventionally, when the electric element is regarded as an upper part of the electric component, the lowest limit of the planned parts to be covered with the coating resin on the terminals is regarded as a standard line, and a releasing agent is coated on lower parts below the standard line so as not to allow the coating to stick on the parts coated with the releasing agent on the terminals, whereby the positions covered with the coating resin on the terminals are adjusted.
However, in the conventional method for covering the electric component with the resin, when the terminals are coated with the releasing agent, it is possible for the releasing agent to be stuck on the terminals, on the side toward the electric element, over the standard line which is the lowest limit of the planned parts to be covered with the coating resin on the terminals, by spreading of the releasing agent or the like. When the electric component having the releasing agent stuck on the terminals over the standard line is covered with the coating resin by dipping into a resin such as a melted epoxy resin, the lowest limit of the parts covered with the coating resin on the terminals is too close to the electric element rather than being at the standard line, so that an amount of the stuck resin decreases as compared with the predetermined amount. Since the strength of the coating resin is proportional to the amount of the stuck resin, the strength of the coating resin of the electric component decreases as compared with the predetermined strength. Thus, by an impact applied from the outside thereof, it is likely to break the coating resin and to deteriorate the airtightness of the electric component.
Also, when decreasing the strength of the coating resin, it is likely that the electric element is not entirely protected by the coating resin against an impact applied from the outside, it is likely that the electric element is broken or chipped.
Furthermore, when breaking the coating resin and deteriorating the airtightness of the electric component, it is likely that moisture, dust and the like are stuck on the electric element and the characteristic of the electric element is deteriorated. Also, in an electric component such a piezoelectric vibrating component or the like, when deteriorating the airtightness, it is likely to cause troubles that the resonance frequency is shifted, a desirable characteristic is not obtained and so on.